By Laura Landro

The outbreak of listeriosis linked to cantaloupes from a Colorado farm field is heightening concerns over its presence in other foods–especially those founds behind the deli counter.

Food-safety experts warn consumers to be aware that listeria, a common environmental bacterium, is linked primarily with meat and animal products, as well as with dairy products such as soft or surface-ripened cheeses such as brie and feta.

In a report in April, the University of Florida’s Emerging Pathogens Institute ranked deli meat as the third-highest combination of food and disease-causing micro-organisms in terms of disease burden. Listeria in dairy products ranks fifth among pathogen-food combinations, mainly due to soft ripened cheeses including queso fresco, a traditional fresh cheese, usually made with unpasteurized milk, common in Mexican cuisine.

Michael Batz, a co-author of the report, tells the Health Blog that there have been significant gains over the past decade in reducing contamination rates of pre-sliced, packaged deli meats, but that retail-sliced deli meats have significantly higher prevalence and levels of listeria, and risks from retail-sliced deli meats are nearly five times higher than prepackaged equivalents, and responsible for 70% of the deaths due to the category.

Batz says many of the conditions found behind the deli counter are conducive to listeria, which unlike other organisms, can grow in the refrigerator. It can be spread by worker’s hands and colonize in cracks, food preparation areas and food-filled crevices on meat and cheese slicers, which is a challenge to sanitation procedures. He advises consumers to keep their own refrigerators extremely clean, and eat deli meats within three or four days, or by the date stamped on the package at the point of purchase. “From the minute you buy deli meats, there’s a window of opportunity for things to get in there,” says Batz.

Consumers can take safety precaution at home, such as keeping uncooked meats separate from vegetables and both separate from cooked foods and ready-to-eat foods, avoiding unpasteurized milk or foods made from raw milk, and following labels on use-by dates. Those at special risk might want to avoid deli meats or stick to pre-packaged deli meats, which are prepared with additives that can inhibit the growth of organisms.

Recent recalls of deli products linked to listeria include a May recall of about 16,000 lbs of pastrami and roast beef in California, and a recall in August 2010 of close to 400,000 lbs of deli meat by a Buffalo company. In June of the same year, 500,000 pounds of hog head cheese — a meat jelly made from swine heads and feet – were recalled after a listeria outbreak linked to the ready-to-eat product in Louisiana.

Of course, the risks of contracting listeria are still relatively low, and outbreaks are less common than other foodborne diseases such as salmonella and E. coli. The latest Centers for Disease Control and Prevention report on foodborne illness in the U.S. shows that laboratory confirmed cases of listeria dropped 38% last year compared to the 1996-1998 period.

But the bug can cause listeriosis, an uncommon but potentially fatal disease, as well as high fever, severe headache, neck stiffness and nausea. Listeriosis can also cause miscarriages and stillbirths, as well as serious and sometimes fatal infections in those with weakened immune systems, such as infants, the elderly and persons with HIV infection or undergoing chemotherapy. Michael Osterholm, a food safety expert at the University of Minnesota, says that even if the overall rate of contamination continues to drop, “we could see an increase in serious illness because of an aging population and an increasing number of people alive today who are immuno-compromised.”

Osterholm advises consumers to ask for health-department inspection records at local delicatessens and restaurants and to be judicious in choosing retail food establishments. “If you walk into a place you can usually tell if there are problems, and if there are, don’t eat there,” he says.

But Osterholm says consumers can’t be expected to be responsible for keeping foods pathogen-free. A new food-safety law enacted earlier this year would give the Food and Drug Administration new powers to set safety standards, conduct inspections and tracing programs and recall food. But without sufficient funding from Congress, Osterholm warns, the FDA won’t have the resources to enforce the law. “Sometimes you can do things to protect yourself, but when we buy produce or get cold cuts from the delicatessen we have to expect that someone else has done that or we’re going to have to stop eating,” he says.

Comments (3 of 3)

Listeria hysteria. It is unfortunate the a few people have died, but this needs to be put into perspective. Listeria is not uncommon, and exists all around us. It is in the soil, and has occurred in such varied foods as hot dogs, deli meats, raw milk, cheeses (particularly soft-ripened cheeses like feta, Brie, Camembert, blue-veined, or Mexican-style “queso blanco”), raw and cooked poultry, raw meats, ice cream, raw vegetables, raw and smoked fish.

On average, 7 per 1,000,000 healthy people are reported to be infected with virulent listeria each year. Given a population of approximately 300 million, that's roughly over two thousand. And those are only the reported cases. Many more probably go unreported, as people think they just have a "stomach flu" and get over it. More people catch, and die from, the common flu. And yet, when a product of business enterprise is in anyway linked to something like this, there is a media tendency to "pile on".

Most food illness can be prevented or avoided by observing simple sanitary practices and proper cooking methods. Wash hands between food preparation steps. Wash fruits and vegetables. Cook meets to 165 degrees F. Do not cross-contaminate foods/preparation surfaces. A little common sense can avoid a lot of the sensationalism.

1:38 pm October 4, 2011

Nevra wrote :

Eliezer - thanks for sharing that link!
WSJ - I also thank you for good reporting that goes beyond just stating what happened, but also puts things into proper perspective. The only part that I think is still misleading is the part about the raw milk and cheeses. My own research has led me to conclude that the risk of liseriosis from raw dairy is negligible - even for those of us in "special groups" (I'm pregnant). Here's my report: http://churnyourown.wordpress.com/2011/09/28/listeria/. That's why I think that your advice to readers to "avoiding unpasteurized milk or foods made from raw milk," is misguided. But other than that, I agree with everything else you say.